Pickering emulsions stabilized by amphiphilic carbonaceous materials derived from wheat straw

Amphiphilic carbonaceous materials CM-1 and CM-2 were synthesized through the hydrothermal carbonization (HTC) of wheat straw powder. The samples were examined by scanning electron microscopy, Fourier-transform infrared spectroscopy and elemental analysis. The results showed that acid concentration and temperature greatly affected the surface properties and wettability of the carbonaceous materials during hydrothermal carbonization. The carbonaceous materials were then used to stabilize Pickering emulsions. CM-1 generated oil- in-water (O/W) Pickering emulsions, while CM-2 generated water-in-oil (W/O) Pickering emulsions. The effects of homogenization speed, particle concentration, dispersed phase to continuous phase volume ratio, pH, and oil type on the morphology, droplet size, size distribution, and stability of the emulsions were investigated. The obtained emulsions exhibited remarkable stability and were easily separated by filtration. This novel strategy for preparing emulsions using CM-1 and CM-2 was highly advantageous for the recovery and reuse of stabilizers.